This technique is easy to integrate into the existing process while being suitable for use with all glass types.
Glass has been used by mankind for many years. It is a versatile raw material that can be moulded into practically any shape and is also so far more resistant too chemicals than most other substances. It is the perfect material for the preservation of foodstuff. Besides the ease of moulding, it is also easy to decorate and color it.
As a result it is also highly suitable for the manufacture of decorative items. These stretch from the production of high quality champagne bottles and wine glasses, decorative perfume bottles right through to vases and statues made gracefully crafted glass. Such articles must have an absolutely perfect surface as even the smallest imperfection will spoil the overall impression of the object. These high quality demands can only be achieved by means of polishing. The use of acid polishing is a common practice to achieve these goals. However, its use results in an additional process step as well as a hazard to both staff and the environment. The disposal costs of this waste acid are also rising continuously. Fire polishing is an alternative to acid polishing. Its most important advantages are:
·no disposal of waste products
·can be integrated into the forming section
·environmentally friendly and reduced health risks
With fire polishing the surface or edge of an already moulded glass shape is remelted using a small burner. This is performed on a carousel directly coupled to the moulding step (which could be a mechanical press, blowing or centrifugal casting). Here the glass is still hot but no longer malleable.
Through the rapid melting of the glass surface, defects like white beads, tool marks and streaks as well as small breakages and sharp edges are smoothed out without thermally stressing the structure. Only a very thin layer is melted, which solidifies just as rapidly again. The result is an immaculate and brilliant surface.
Small oxy-fuel burners are particularly well suited to heating small precisely defined surfaces to a high temperature in a short space of time. They make it possible to heat a specific part of the glass surface without heating the entire structure and thereby damaging it. Messer manufactures a large part of different types of burners that are capable of coping with a broad spectrum of applications. The primary characteristic of these burners is their layout, size and version can however also be adapted to suit the individual requirements.
There are burners with internal and outside mixing. In the first type of burner the fuel gas and oxygen are premixed within an internal mixing zone prior to being ignited at the burner head. Premixed burners, type Griflam of Messer Cutting and Welding have been successfully used in the glass industry especially in the field of quartz glass treatment for many years.
Outside burners have been developed in recent years. Both the fuel gas and the oxygen are lead to the front exit plate on the burner head through separate holes. The mixing of the two gas streams therefore occurs outside the burner. The newly introduced model that was developed by our co-operation partner is producing excellent results. Crystal and lead crystal glass in particular have shown an immaculate surface, no damage to the sharp edges of decorations and a high brilliance.
MESSER GRIESHEIM GmbH
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